Personal cleansing compositions have been developed for use in showers, such as shower gels. However, large numbers of people prefer to use a conventional bar of soap rather than a shower gel. It is believed that one factor responsible for resistance to the use of shower gels is connected to lather generation. In order to produce lather from a shower gel the user must apply shear to the gel. In some cases much of this effort is wasted as the lather washes away before it can be applied to the body.
In order to deal with the problem it is known to provide a shower gel which creates lather as soon as possible after the gel is dispensed from the package.
WO 96/09032A discloses a soap-free post-foaming gel composition which is particularly intended for shaving using a razor. The composition utilises a volatile hydrocarbon such as isopentane to provide a gel structure. Although this composition is satisfactory for its intended purpose it does not perform well for personal washing mainly because it gives an uncomfortable ‘stripped’ feeling to the skin.
WO 97/03646 discloses a post-foaming gel composition for use in an aerosol container wherein the composition comprises a base material having a viscosity of at least 9500 cps to which is added a foam-forming propellant gas. Whilst this composition has good personal washing properties its viscous nature makes it particularly difficult to process and package and thus there is a high degree of wastage during manufacture.
Attempts have been made to address this problem. For example, WO00/39273 discloses a post-foaming composition of low viscosity which gels upon addition of the post-foaming agent. However, this sudden, instantaneous gelling can make the composition difficult to fill into suitable packaging and may lead to stoppages and breakdowns in the pipe-work of the production plant machinery resulting in plant downtime and inefficient production. This formulation must be filled into required packaging immediately on addition of the post-foaming agent.
Similarly, GB 2,213,160 teaches of a post foaming gel product containing an anionic surfactant and a non-ionic, ethoxylated fatty alcohol or ester. The product gels on addition of post-foaming agent and forms a viscous gel prior to filling into a suitable container. This again presents difficulties in terms of manufacturing due to the high viscosity of the gel formed.
WO 02/05758 discloses a self foaming composition wherein the composition is in the form of a liquid crystalline structure. This results in a soft gel of lower viscosity. Whilst the soft gel is easier to spread onto the skin it has a number of disadvantages compared to a more structured viscous gel. A more viscous gel will release the post-foaming agent more slowly on agitation and lather is developed in a more controlled manner. Thus it appears that the user is responsible for creating the foam as with conventional cleaning materials and the composition is perceived as providing the behaviour expected for a good cleaning operation. The lather generated from a more viscous gel is creamier than that generated from a soft gel. An additional benefit of a viscous gel is that the product can be spread further over the body without being washed away as with conventional products. Thus, it appears to the user that the product is more economical.
Many of the post-foaming compositions currently available have an opaque or cloudy appearance. This provides poor visual differentiation between the initial gel which is dispensed and the lather generated when the gel is spread onto the skin. As such, these compositions lack visual appeal.
It is desirable therefore to provide a post-foaming cleansing composition which is sufficiently mobile to facilitate easy processing and packaging, but which has a stable, clear, viscous gel structure when dispensed from its packaging and which enables slow release of a post-foaming agent and provides a creamy lather. It is also desirable to provide a post-foaming cleansing composition which gives acceptable post washing skin feel i.e. does not the leave the skin feeling dry and tight.